1. Field of Invention
The disclosure relates to a light emitting device, and more particularly to a light emitting device having at least one light emitting diode (LED) module comprising a plurality of LEDs and disposed on a substrate.
2. Related Art
Rapid progress of technologies results in rapid development for electronic products. LEDs have been widely applied in illumination devices to serve as the light source for illumination.
Due to advantages of being durable and light, and having long service life and low power consumption, the LEDs have become the mainstream of the illumination industry and the semiconductor industry. Generally, the LEDs can be used in illumination devices, backlight modules of liquid crystal displays (LCDs), or light sources of indicating lamps. However, in practice, the current LED light sources can only operate in the condition that direct current (DC) power supply exists. This indicates the LED light source cannot be used in the alternating current (AC) power supplies. Such technical problems limit LED applications.
Accordingly, AC LEDs capable of using an AC power supply have been developed in the industry. Through a design of the architecture of bridge-rectifying, the AC LEDs can directly use an AC power supply for driving. Generally, in the conditions that the AC power supply having positive cycles and a negative cycles, LEDs are partially conducted, and the non-conducted LEDs have to endure a reverse bias voltage. In this case, the LEDs endure the reverse bias voltage alternately, and when the reverse bias voltage is excessively high, a leakage current of the high reverse biased voltage is generated, thereby resulting in breakdown of LED dies or influencing the illumination lifetime of the entire LEDs, and reducing the reliability.
Secondly, as mentioned above, the LEDs driven through bridge rectifying cannot be lighted up simultaneously, that is to say, only ½ LED can be lighted up, such that the payload of the LEDs is significantly reduced, thereby influencing the illumination benefit.
Accordingly, persons in the art are in urgent need of finding solutions to solve the problem that the withstand voltage of the conventional AC LEDs is limited and provide a light emitting device that can endure the commercial power with high voltage input and has high payload.